FFmpeg
4xm.c
Go to the documentation of this file.
1 /*
2  * 4X Technologies .4xm File Demuxer (no muxer)
3  * Copyright (c) 2003 The FFmpeg project
4  *
5  * This file is part of FFmpeg.
6  *
7  * FFmpeg is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * FFmpeg is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with FFmpeg; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
22 /**
23  * @file
24  * 4X Technologies file demuxer
25  * by Mike Melanson (melanson@pcisys.net)
26  * for more information on the .4xm file format, visit:
27  * http://www.pcisys.net/~melanson/codecs/
28  */
29 
30 #include "libavutil/intreadwrite.h"
31 #include "libavutil/intfloat.h"
32 #include "libavutil/mem.h"
33 #include "libavcodec/internal.h"
34 #include "avformat.h"
35 #include "demux.h"
36 #include "internal.h"
37 
38 #define RIFF_TAG MKTAG('R', 'I', 'F', 'F')
39 #define FOURXMV_TAG MKTAG('4', 'X', 'M', 'V')
40 #define LIST_TAG MKTAG('L', 'I', 'S', 'T')
41 #define HEAD_TAG MKTAG('H', 'E', 'A', 'D')
42 #define TRK__TAG MKTAG('T', 'R', 'K', '_')
43 #define MOVI_TAG MKTAG('M', 'O', 'V', 'I')
44 #define VTRK_TAG MKTAG('V', 'T', 'R', 'K')
45 #define STRK_TAG MKTAG('S', 'T', 'R', 'K')
46 #define std__TAG MKTAG('s', 't', 'd', '_')
47 #define name_TAG MKTAG('n', 'a', 'm', 'e')
48 #define vtrk_TAG MKTAG('v', 't', 'r', 'k')
49 #define strk_TAG MKTAG('s', 't', 'r', 'k')
50 #define ifrm_TAG MKTAG('i', 'f', 'r', 'm')
51 #define pfrm_TAG MKTAG('p', 'f', 'r', 'm')
52 #define cfrm_TAG MKTAG('c', 'f', 'r', 'm')
53 #define ifr2_TAG MKTAG('i', 'f', 'r', '2')
54 #define pfr2_TAG MKTAG('p', 'f', 'r', '2')
55 #define cfr2_TAG MKTAG('c', 'f', 'r', '2')
56 #define snd__TAG MKTAG('s', 'n', 'd', '_')
57 
58 #define vtrk_SIZE 0x44
59 #define strk_SIZE 0x28
60 
61 #define GET_LIST_HEADER() \
62  fourcc_tag = avio_rl32(pb); \
63  size = avio_rl32(pb); \
64  if (fourcc_tag != LIST_TAG) { \
65  ret = AVERROR_INVALIDDATA; \
66  goto fail; \
67  } \
68  fourcc_tag = avio_rl32(pb);
69 
70 typedef struct AudioTrack {
72  int bits;
73  int channels;
75  int adpcm;
76  int64_t audio_pts;
77 } AudioTrack;
78 
79 typedef struct FourxmDemuxContext {
83 
84  int64_t video_pts;
87 
88 static int fourxm_probe(const AVProbeData *p)
89 {
90  if ((AV_RL32(&p->buf[0]) != RIFF_TAG) ||
91  (AV_RL32(&p->buf[8]) != FOURXMV_TAG))
92  return 0;
93 
94  return AVPROBE_SCORE_MAX;
95 }
96 
98  FourxmDemuxContext *fourxm, uint8_t *buf, int size,
99  int left)
100 {
101  AVStream *st;
102  /* check that there is enough data */
103  if (size != vtrk_SIZE || left < size + 8) {
104  return AVERROR_INVALIDDATA;
105  }
106 
107  /* allocate a new AVStream */
108  st = avformat_new_stream(s, NULL);
109  if (!st)
110  return AVERROR(ENOMEM);
111 
112  avpriv_set_pts_info(st, 60, fourxm->fps.den, fourxm->fps.num);
113 
114  fourxm->video_stream_index = st->index;
115 
118 
120  if (!st->codecpar->extradata)
121  return AVERROR(ENOMEM);
122  st->codecpar->extradata_size = 4;
123  AV_WL32(st->codecpar->extradata, AV_RL32(buf + 16));
124  st->codecpar->width = AV_RL32(buf + 36);
125  st->codecpar->height = AV_RL32(buf + 40);
126 
127  return 0;
128 }
129 
130 
132  FourxmDemuxContext *fourxm, uint8_t *buf, int size,
133  int left)
134 {
135  AVStream *st;
136  int track;
137  /* check that there is enough data */
138  if (size != strk_SIZE || left < size + 8)
139  return AVERROR_INVALIDDATA;
140 
141  track = AV_RL32(buf + 8);
142  if ((unsigned)track >= UINT_MAX / sizeof(AudioTrack) - 1 ||
143  track >= s->max_streams) {
144  av_log(s, AV_LOG_ERROR, "current_track too large\n");
145  return AVERROR_INVALIDDATA;
146  }
147 
148  if (track + 1 > fourxm->track_count) {
149  if (av_reallocp_array(&fourxm->tracks, track + 1, sizeof(AudioTrack)))
150  return AVERROR(ENOMEM);
151  memset(&fourxm->tracks[fourxm->track_count], 0,
152  sizeof(AudioTrack) * (track + 1 - fourxm->track_count));
153  fourxm->track_count = track + 1;
154  } else {
155  if (fourxm->tracks[track].bits)
156  return AVERROR_INVALIDDATA;
157  }
158  fourxm->tracks[track].adpcm = AV_RL32(buf + 12);
159  fourxm->tracks[track].channels = AV_RL32(buf + 36);
160  fourxm->tracks[track].sample_rate = AV_RL32(buf + 40);
161  fourxm->tracks[track].bits = AV_RL32(buf + 44);
162  fourxm->tracks[track].audio_pts = 0;
163 
164  if (fourxm->tracks[track].channels <= 0 ||
165  fourxm->tracks[track].channels > FF_SANE_NB_CHANNELS ||
166  fourxm->tracks[track].sample_rate <= 0 ||
167  fourxm->tracks[track].bits <= 0 ||
168  fourxm->tracks[track].bits > INT_MAX / FF_SANE_NB_CHANNELS) {
169  av_log(s, AV_LOG_ERROR, "audio header invalid\n");
170  return AVERROR_INVALIDDATA;
171  }
172  if (!fourxm->tracks[track].adpcm && fourxm->tracks[track].bits<8) {
173  av_log(s, AV_LOG_ERROR, "bits unspecified for non ADPCM\n");
174  return AVERROR_INVALIDDATA;
175  }
176 
177  if (fourxm->tracks[track].sample_rate > INT64_MAX / fourxm->tracks[track].bits / fourxm->tracks[track].channels) {
178  av_log(s, AV_LOG_ERROR, "Overflow during bit rate calculation %d * %d * %d\n",
179  fourxm->tracks[track].sample_rate, fourxm->tracks[track].bits, fourxm->tracks[track].channels);
180  return AVERROR_INVALIDDATA;
181  }
182 
183  /* allocate a new AVStream */
184  st = avformat_new_stream(s, NULL);
185  if (!st)
186  return AVERROR(ENOMEM);
187 
188  st->id = track;
189  avpriv_set_pts_info(st, 60, 1, fourxm->tracks[track].sample_rate);
190 
191  fourxm->tracks[track].stream_index = st->index;
192 
194  st->codecpar->codec_tag = 0;
195  st->codecpar->ch_layout.nb_channels = fourxm->tracks[track].channels;
196  st->codecpar->sample_rate = fourxm->tracks[track].sample_rate;
197  st->codecpar->bits_per_coded_sample = fourxm->tracks[track].bits;
198  st->codecpar->bit_rate = (int64_t)st->codecpar->ch_layout.nb_channels *
199  st->codecpar->sample_rate *
203 
204  if (fourxm->tracks[track].adpcm){
206  } else if (st->codecpar->bits_per_coded_sample == 8) {
208  } else
210 
211  return 0;
212 }
213 
215 {
216  AVIOContext *pb = s->pb;
217  unsigned int fourcc_tag;
218  unsigned int size;
219  int header_size;
220  FourxmDemuxContext *fourxm = s->priv_data;
221  unsigned char *header = NULL;
222  int i, ret;
223 
224  fourxm->track_count = 0;
225  fourxm->tracks = NULL;
226  fourxm->fps = (AVRational){1,1};
227  fourxm->video_stream_index = -1;
228 
229  /* skip the first 3 32-bit numbers */
230  avio_skip(pb, 12);
231 
232  /* check for LIST-HEAD */
233  GET_LIST_HEADER();
234  header_size = size - 4;
235  if (fourcc_tag != HEAD_TAG || header_size < 0)
236  return AVERROR_INVALIDDATA;
237 
238  /* allocate space for the header and load the whole thing */
239  header = av_malloc(header_size);
240  if (!header)
241  return AVERROR(ENOMEM);
242  if (avio_read(pb, header, header_size) != header_size) {
243  av_free(header);
244  return AVERROR(EIO);
245  }
246 
247  /* take the lazy approach and search for any and all vtrk and strk chunks */
248  for (i = 0; i < header_size - 8; i++) {
249  fourcc_tag = AV_RL32(&header[i]);
250  size = AV_RL32(&header[i + 4]);
251  if (size > header_size - i - 8 && (fourcc_tag == vtrk_TAG || fourcc_tag == strk_TAG)) {
252  av_log(s, AV_LOG_ERROR, "chunk larger than array %d>%d\n", size, header_size - i - 8);
254  goto fail;
255  }
256 
257  if (fourcc_tag == std__TAG) {
258  if (header_size - i < 16) {
259  av_log(s, AV_LOG_ERROR, "std TAG truncated\n");
261  goto fail;
262  }
263  fourxm->fps = av_d2q(av_int2float(AV_RL32(&header[i + 12])), 10000);
264  } else if (fourcc_tag == vtrk_TAG) {
265  if ((ret = parse_vtrk(s, fourxm, header + i, size,
266  header_size - i)) < 0)
267  goto fail;
268 
269  i += 8 + size;
270  } else if (fourcc_tag == strk_TAG) {
271  if ((ret = parse_strk(s, fourxm, header + i, size,
272  header_size - i)) < 0)
273  goto fail;
274 
275  i += 8 + size;
276  }
277  }
278 
279  /* skip over the LIST-MOVI chunk (which is where the stream should be */
280  GET_LIST_HEADER();
281  if (fourcc_tag != MOVI_TAG) {
283  goto fail;
284  }
285 
286  av_free(header);
287  /* initialize context members */
288  fourxm->video_pts = -1; /* first frame will push to 0 */
289 
290  return 0;
291 fail:
292  av_free(header);
293  return ret;
294 }
295 
297  AVPacket *pkt)
298 {
299  FourxmDemuxContext *fourxm = s->priv_data;
300  AVIOContext *pb = s->pb;
301  unsigned int fourcc_tag;
302  unsigned int size;
303  int ret = 0;
304  unsigned int track_number;
305  int packet_read = 0;
306  unsigned char header[8];
307  int64_t audio_frame_count;
308 
309  while (!packet_read) {
310  if ((ret = avio_read(s->pb, header, 8)) < 0)
311  return ret;
312  fourcc_tag = AV_RL32(&header[0]);
313  size = AV_RL32(&header[4]);
314  if (avio_feof(pb))
315  return AVERROR(EIO);
316  switch (fourcc_tag) {
317  case LIST_TAG:
318  /* this is a good time to bump the video pts */
319  fourxm->video_pts++;
320 
321  /* skip the LIST-* tag and move on to the next fourcc */
322  avio_rl32(pb);
323  break;
324 
325  case ifrm_TAG:
326  case pfrm_TAG:
327  case cfrm_TAG:
328  case ifr2_TAG:
329  case pfr2_TAG:
330  case cfr2_TAG:
331  /* allocate 8 more bytes than 'size' to account for fourcc
332  * and size */
333  if (size > INT_MAX - AV_INPUT_BUFFER_PADDING_SIZE - 8)
334  return AVERROR_INVALIDDATA;
335  if (fourxm->video_stream_index < 0)
336  return AVERROR_INVALIDDATA;
337  if ((ret = av_new_packet(pkt, size + 8)) < 0)
338  return ret;
340  pkt->pts = fourxm->video_pts;
341  pkt->pos = avio_tell(s->pb);
342  memcpy(pkt->data, header, 8);
343  ret = avio_read(s->pb, &pkt->data[8], size);
344 
345  if (ret < 0) {
347  } else {
348  packet_read = 1;
349  av_shrink_packet(pkt, ret + 8);
350  }
351  break;
352 
353  case snd__TAG:
354  track_number = avio_rl32(pb);
355  avio_skip(pb, 4);
356  size -= 8;
357 
358  if (track_number < fourxm->track_count &&
359  fourxm->tracks[track_number].channels > 0) {
360  ret = av_get_packet(s->pb, pkt, size);
361  if (ret < 0)
362  return ret;
363  pkt->stream_index =
364  fourxm->tracks[track_number].stream_index;
365  pkt->pts = fourxm->tracks[track_number].audio_pts;
366  packet_read = 1;
367 
368  /* pts accounting */
370  if (fourxm->tracks[track_number].adpcm)
371  audio_frame_count -= 2 * (fourxm->tracks[track_number].channels);
372  audio_frame_count /= fourxm->tracks[track_number].channels;
373  if (fourxm->tracks[track_number].adpcm) {
374  audio_frame_count *= 2;
375  } else
377  (fourxm->tracks[track_number].bits / 8);
378  fourxm->tracks[track_number].audio_pts += audio_frame_count;
379  } else {
380  avio_skip(pb, size);
381  }
382  break;
383 
384  default:
385  avio_skip(pb, size);
386  break;
387  }
388  }
389  return ret;
390 }
391 
393 {
394  FourxmDemuxContext *fourxm = s->priv_data;
395 
396  av_freep(&fourxm->tracks);
397 
398  return 0;
399 }
400 
402  .p.name = "4xm",
403  .p.long_name = NULL_IF_CONFIG_SMALL("4X Technologies"),
404  .priv_data_size = sizeof(FourxmDemuxContext),
405  .flags_internal = FF_INFMT_FLAG_INIT_CLEANUP,
410 };
AV_CODEC_ID_PCM_S16LE
@ AV_CODEC_ID_PCM_S16LE
Definition: codec_id.h:328
av_packet_unref
void av_packet_unref(AVPacket *pkt)
Wipe the packet.
Definition: packet.c:427
fourxm_read_packet
static int fourxm_read_packet(AVFormatContext *s, AVPacket *pkt)
Definition: 4xm.c:296
AVCodecParameters::extradata
uint8_t * extradata
Extra binary data needed for initializing the decoder, codec-dependent.
Definition: codec_par.h:69
AudioTrack::adpcm
int adpcm
Definition: 4xm.c:75
AudioTrack::audio_pts
int64_t audio_pts
Definition: 4xm.c:76
FourxmDemuxContext::tracks
AudioTrack * tracks
Definition: 4xm.c:82
FourxmDemuxContext::video_pts
int64_t video_pts
Definition: 4xm.c:84
AVERROR
Filter the word “frame” indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later. That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another. Frame references ownership and permissions
AVCodecParameters::codec_type
enum AVMediaType codec_type
General type of the encoded data.
Definition: codec_par.h:51
AV_WL32
#define AV_WL32(p, v)
Definition: intreadwrite.h:424
avformat_new_stream
AVStream * avformat_new_stream(AVFormatContext *s, const struct AVCodec *c)
Add a new stream to a media file.
internal.h
AVPacket::data
uint8_t * data
Definition: packet.h:524
AVCodecParameters::codec_tag
uint32_t codec_tag
Additional information about the codec (corresponds to the AVI FOURCC).
Definition: codec_par.h:59
AVChannelLayout::nb_channels
int nb_channels
Number of channels in this layout.
Definition: channel_layout.h:313
intfloat.h
AudioTrack::sample_rate
int sample_rate
Definition: 4xm.c:71
av_malloc
#define av_malloc(s)
Definition: tableprint_vlc.h:30
AVPROBE_SCORE_MAX
#define AVPROBE_SCORE_MAX
maximum score
Definition: avformat.h:463
avpriv_set_pts_info
void avpriv_set_pts_info(AVStream *st, int pts_wrap_bits, unsigned int pts_num, unsigned int pts_den)
Set the time base and wrapping info for a given stream.
Definition: avformat.c:853
fourxm_probe
static int fourxm_probe(const AVProbeData *p)
Definition: 4xm.c:88
fail
#define fail()
Definition: checkasm.h:182
av_int2float
static av_always_inline float av_int2float(uint32_t i)
Reinterpret a 32-bit integer as a float.
Definition: intfloat.h:40
av_shrink_packet
void av_shrink_packet(AVPacket *pkt, int size)
Reduce packet size, correctly zeroing padding.
Definition: packet.c:113
fourxm_read_header
static int fourxm_read_header(AVFormatContext *s)
Definition: 4xm.c:214
read_close
static av_cold int read_close(AVFormatContext *ctx)
Definition: libcdio.c:143
avio_tell
static av_always_inline int64_t avio_tell(AVIOContext *s)
ftell() equivalent for AVIOContext.
Definition: avio.h:494
pfrm_TAG
#define pfrm_TAG
Definition: 4xm.c:51
AudioTrack::channels
int channels
Definition: 4xm.c:73
HEAD_TAG
#define HEAD_TAG
Definition: 4xm.c:41
AVRational::num
int num
Numerator.
Definition: rational.h:59
cfrm_TAG
#define cfrm_TAG
Definition: 4xm.c:52
pkt
AVPacket * pkt
Definition: movenc.c:60
AV_LOG_ERROR
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:180
read_packet
static int read_packet(void *opaque, uint8_t *buf, int buf_size)
Definition: avio_read_callback.c:42
FOURXMV_TAG
#define FOURXMV_TAG
Definition: 4xm.c:39
snd__TAG
#define snd__TAG
Definition: 4xm.c:56
MOVI_TAG
#define MOVI_TAG
Definition: 4xm.c:43
AV_CODEC_ID_4XM
@ AV_CODEC_ID_4XM
Definition: codec_id.h:86
intreadwrite.h
s
#define s(width, name)
Definition: cbs_vp9.c:198
av_new_packet
int av_new_packet(AVPacket *pkt, int size)
Allocate the payload of a packet and initialize its fields with default values.
Definition: packet.c:98
AVInputFormat::name
const char * name
A comma separated list of short names for the format.
Definition: avformat.h:553
AVProbeData::buf
unsigned char * buf
Buffer must have AVPROBE_PADDING_SIZE of extra allocated bytes filled with zero.
Definition: avformat.h:453
AVMEDIA_TYPE_AUDIO
@ AVMEDIA_TYPE_AUDIO
Definition: avutil.h:202
AVCodecParameters::width
int width
Video only.
Definition: codec_par.h:134
audio_frame_count
static int audio_frame_count
Definition: demux_decode.c:57
vtrk_SIZE
#define vtrk_SIZE
Definition: 4xm.c:58
strk_TAG
#define strk_TAG
Definition: 4xm.c:49
if
if(ret)
Definition: filter_design.txt:179
FF_INFMT_FLAG_INIT_CLEANUP
#define FF_INFMT_FLAG_INIT_CLEANUP
For an FFInputFormat with this flag set read_close() needs to be called by the caller upon read_heade...
Definition: demux.h:35
AVFormatContext
Format I/O context.
Definition: avformat.h:1255
AVStream::codecpar
AVCodecParameters * codecpar
Codec parameters associated with this stream.
Definition: avformat.h:766
read_header
static int read_header(FFV1Context *f)
Definition: ffv1dec.c:550
NULL
#define NULL
Definition: coverity.c:32
fourxm_read_close
static int fourxm_read_close(AVFormatContext *s)
Definition: 4xm.c:392
parse_strk
static int parse_strk(AVFormatContext *s, FourxmDemuxContext *fourxm, uint8_t *buf, int size, int left)
Definition: 4xm.c:131
AVRational
Rational number (pair of numerator and denominator).
Definition: rational.h:58
FourxmDemuxContext::fps
AVRational fps
Definition: 4xm.c:85
strk_SIZE
#define strk_SIZE
Definition: 4xm.c:59
AVProbeData
This structure contains the data a format has to probe a file.
Definition: avformat.h:451
RIFF_TAG
#define RIFF_TAG
Definition: 4xm.c:38
AVCodecParameters::ch_layout
AVChannelLayout ch_layout
Audio only.
Definition: codec_par.h:180
FourxmDemuxContext::video_stream_index
int video_stream_index
Definition: 4xm.c:80
AVCodecParameters::sample_rate
int sample_rate
Audio only.
Definition: codec_par.h:184
AVCodecParameters::extradata_size
int extradata_size
Size of the extradata content in bytes.
Definition: codec_par.h:73
AudioTrack
Definition: 4xm.c:70
avio_rl32
unsigned int avio_rl32(AVIOContext *s)
Definition: aviobuf.c:730
AVIOContext
Bytestream IO Context.
Definition: avio.h:160
NULL_IF_CONFIG_SMALL
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification.
Definition: internal.h:94
size
int size
Definition: twinvq_data.h:10344
cfr2_TAG
#define cfr2_TAG
Definition: 4xm.c:55
vtrk_TAG
#define vtrk_TAG
Definition: 4xm.c:48
ff_fourxm_demuxer
const FFInputFormat ff_fourxm_demuxer
Definition: 4xm.c:401
FFInputFormat::p
AVInputFormat p
The public AVInputFormat.
Definition: demux.h:41
header
static const uint8_t header[24]
Definition: sdr2.c:68
av_reallocp_array
int av_reallocp_array(void *ptr, size_t nmemb, size_t size)
Allocate, reallocate an array through a pointer to a pointer.
Definition: mem.c:225
parse_vtrk
static int parse_vtrk(AVFormatContext *s, FourxmDemuxContext *fourxm, uint8_t *buf, int size, int left)
Definition: 4xm.c:97
AudioTrack::stream_index
int stream_index
Definition: 4xm.c:74
GET_LIST_HEADER
#define GET_LIST_HEADER()
Definition: 4xm.c:61
i
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:256
AVPacket::pts
int64_t pts
Presentation timestamp in AVStream->time_base units; the time at which the decompressed packet will b...
Definition: packet.h:517
AVCodecParameters::height
int height
Definition: codec_par.h:135
AVCodecParameters::block_align
int block_align
Audio only.
Definition: codec_par.h:191
av_d2q
AVRational av_d2q(double d, int max)
Convert a double precision floating point number to a rational.
Definition: rational.c:106
av_mallocz
void * av_mallocz(size_t size)
Allocate a memory block with alignment suitable for all memory accesses (including vectors if availab...
Definition: mem.c:256
demux.h
av_get_packet
int av_get_packet(AVIOContext *s, AVPacket *pkt, int size)
Allocate and read the payload of a packet and initialize its fields with default values.
Definition: utils.c:91
FourxmDemuxContext
Definition: 4xm.c:79
AVStream::id
int id
Format-specific stream ID.
Definition: avformat.h:755
ret
ret
Definition: filter_design.txt:187
AVStream
Stream structure.
Definition: avformat.h:743
avformat.h
AudioTrack::bits
int bits
Definition: 4xm.c:72
FourxmDemuxContext::track_count
int track_count
Definition: 4xm.c:81
AV_INPUT_BUFFER_PADDING_SIZE
#define AV_INPUT_BUFFER_PADDING_SIZE
Definition: defs.h:40
left
Tag MUST be and< 10hcoeff half pel interpolation filter coefficients, hcoeff[0] are the 2 middle coefficients[1] are the next outer ones and so on, resulting in a filter like:...eff[2], hcoeff[1], hcoeff[0], hcoeff[0], hcoeff[1], hcoeff[2] ... the sign of the coefficients is not explicitly stored but alternates after each coeff and coeff[0] is positive, so ...,+,-,+,-,+,+,-,+,-,+,... hcoeff[0] is not explicitly stored but found by subtracting the sum of all stored coefficients with signs from 32 hcoeff[0]=32 - hcoeff[1] - hcoeff[2] - ... a good choice for hcoeff and htaps is htaps=6 hcoeff={40,-10, 2} an alternative which requires more computations at both encoder and decoder side and may or may not be better is htaps=8 hcoeff={42,-14, 6,-2}ref_frames minimum of the number of available reference frames and max_ref_frames for example the first frame after a key frame always has ref_frames=1spatial_decomposition_type wavelet type 0 is a 9/7 symmetric compact integer wavelet 1 is a 5/3 symmetric compact integer wavelet others are reserved stored as delta from last, last is reset to 0 if always_reset||keyframeqlog quality(logarithmic quantizer scale) stored as delta from last, last is reset to 0 if always_reset||keyframemv_scale stored as delta from last, last is reset to 0 if always_reset||keyframe FIXME check that everything works fine if this changes between framesqbias dequantization bias stored as delta from last, last is reset to 0 if always_reset||keyframeblock_max_depth maximum depth of the block tree stored as delta from last, last is reset to 0 if always_reset||keyframequant_table quantization tableHighlevel bitstream structure:==============================--------------------------------------------|Header|--------------------------------------------|------------------------------------|||Block0||||split?||||yes no||||......... intra?||||:Block01 :yes no||||:Block02 :....... ..........||||:Block03 ::y DC ::ref index:||||:Block04 ::cb DC ::motion x :||||......... :cr DC ::motion y :||||....... ..........|||------------------------------------||------------------------------------|||Block1|||...|--------------------------------------------|------------ ------------ ------------|||Y subbands||Cb subbands||Cr subbands||||--- ---||--- ---||--- ---|||||LL0||HL0||||LL0||HL0||||LL0||HL0|||||--- ---||--- ---||--- ---||||--- ---||--- ---||--- ---|||||LH0||HH0||||LH0||HH0||||LH0||HH0|||||--- ---||--- ---||--- ---||||--- ---||--- ---||--- ---|||||HL1||LH1||||HL1||LH1||||HL1||LH1|||||--- ---||--- ---||--- ---||||--- ---||--- ---||--- ---|||||HH1||HL2||||HH1||HL2||||HH1||HL2|||||...||...||...|||------------ ------------ ------------|--------------------------------------------Decoding process:=================------------|||Subbands|------------||||------------|Intra DC||||LL0 subband prediction ------------|\ Dequantization ------------------- \||Reference frames|\ IDWT|------- -------|Motion \|||Frame 0||Frame 1||Compensation . OBMC v -------|------- -------|--------------. \------> Frame n output Frame Frame<----------------------------------/|...|------------------- Range Coder:============Binary Range Coder:------------------- The implemented range coder is an adapted version based upon "Range encoding: an algorithm for removing redundancy from a digitised message." by G. N. N. Martin. The symbols encoded by the Snow range coder are bits(0|1). The associated probabilities are not fix but change depending on the symbol mix seen so far. bit seen|new state ---------+----------------------------------------------- 0|256 - state_transition_table[256 - old_state];1|state_transition_table[old_state];state_transition_table={ 0, 0, 0, 0, 0, 0, 0, 0, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 171, 172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 190, 191, 192, 194, 194, 195, 196, 197, 198, 199, 200, 201, 202, 202, 204, 205, 206, 207, 208, 209, 209, 210, 211, 212, 213, 215, 215, 216, 217, 218, 219, 220, 220, 222, 223, 224, 225, 226, 227, 227, 229, 229, 230, 231, 232, 234, 234, 235, 236, 237, 238, 239, 240, 241, 242, 243, 244, 245, 246, 247, 248, 248, 0, 0, 0, 0, 0, 0, 0};FIXME Range Coding of integers:------------------------- FIXME Neighboring Blocks:===================left and top are set to the respective blocks unless they are outside of the image in which case they are set to the Null block top-left is set to the top left block unless it is outside of the image in which case it is set to the left block if this block has no larger parent block or it is at the left side of its parent block and the top right block is not outside of the image then the top right block is used for top-right else the top-left block is used Null block y, cb, cr are 128 level, ref, mx and my are 0 Motion Vector Prediction:=========================1. the motion vectors of all the neighboring blocks are scaled to compensate for the difference of reference frames scaled_mv=(mv *(256 *(current_reference+1)/(mv.reference+1))+128)> the median of the scaled left
Definition: snow.txt:386
AV_RL32
uint64_t_TMPL AV_WL64 unsigned int_TMPL AV_RL32
Definition: bytestream.h:92
AVStream::index
int index
stream index in AVFormatContext
Definition: avformat.h:749
AVRational::den
int den
Denominator.
Definition: rational.h:60
avio_read
int avio_read(AVIOContext *s, unsigned char *buf, int size)
Read size bytes from AVIOContext into buf.
Definition: aviobuf.c:612
AVPacket::stream_index
int stream_index
Definition: packet.h:526
avio_skip
int64_t avio_skip(AVIOContext *s, int64_t offset)
Skip given number of bytes forward.
Definition: aviobuf.c:318
ifrm_TAG
#define ifrm_TAG
Definition: 4xm.c:50
AVMEDIA_TYPE_VIDEO
@ AVMEDIA_TYPE_VIDEO
Definition: avutil.h:201
read_probe
static int read_probe(const AVProbeData *p)
Definition: cdg.c:30
AVCodecParameters::bits_per_coded_sample
int bits_per_coded_sample
The number of bits per sample in the codedwords.
Definition: codec_par.h:110
mem.h
AV_CODEC_ID_PCM_U8
@ AV_CODEC_ID_PCM_U8
Definition: codec_id.h:333
av_free
#define av_free(p)
Definition: tableprint_vlc.h:33
AVCodecParameters::codec_id
enum AVCodecID codec_id
Specific type of the encoded data (the codec used).
Definition: codec_par.h:55
AVPacket
This structure stores compressed data.
Definition: packet.h:501
av_freep
#define av_freep(p)
Definition: tableprint_vlc.h:34
AVPacket::pos
int64_t pos
byte position in stream, -1 if unknown
Definition: packet.h:544
FFInputFormat
Definition: demux.h:37
LIST_TAG
#define LIST_TAG
Definition: 4xm.c:40
AVCodecParameters::bit_rate
int64_t bit_rate
The average bitrate of the encoded data (in bits per second).
Definition: codec_par.h:97
av_log
#define av_log(a,...)
Definition: tableprint_vlc.h:27
AVERROR_INVALIDDATA
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:61
AV_CODEC_ID_ADPCM_4XM
@ AV_CODEC_ID_ADPCM_4XM
Definition: codec_id.h:374
FF_SANE_NB_CHANNELS
#define FF_SANE_NB_CHANNELS
Definition: internal.h:37
std__TAG
#define std__TAG
Definition: 4xm.c:46
ifr2_TAG
#define ifr2_TAG
Definition: 4xm.c:53
pfr2_TAG
#define pfr2_TAG
Definition: 4xm.c:54
avio_feof
int avio_feof(AVIOContext *s)
Similar to feof() but also returns nonzero on read errors.
Definition: aviobuf.c:346